1. Field of the Invention
The present invention relates generally to traffic barriers and, more particularly, to vehicle barriers having a vehicle barricade and a cooperating pivotal signal barrier.
2. Description of the Prior Art
It is known to employ signal barriers such as gate arms as traffic controllers to restrict vehicle passage on a roadway, or to a parking area, and at railroad signal crossings and the like. The function and advantages of such devices are well-known. The disadvantages are that a moving vehicle can crash through the gate arm and, therefore, the gate arm is not a positive physical barricade but rather a deterrent. However, signal barriers are not a deterrent to a terrorist or the like who is willing to go to any extreme to gain access to oil refineries, satellite communication stations, embassies, military bases, and other government installations.
It is known to use vehicle barricades as disclosed, for example, in U.S. Pat. Nos. 4,574,523 and 4,630,395 to the present inventor. The vehicle barricades disclosed are low lying in the roadway and moveable from a generally horizontal to an angularly disposed position for blocking the roadway. The advantages of these devices are that they are constructed to absorb the impact forces caused by the collision of a vehicle therewith. Furthermore, these devices are capable of stopping and preventing further movement of a vehicle, such as a truck loaded with explosives, which would be driven by a terrorist. The disadvantages are that these devices are expensive to construct and install and, because they are low lying, can be inadvertently impacted by an oncoming vehicle if the driver is not attentive. Also, in the event that such device would fail in the angularly disposed position, an inadvertent driver might drive his vehicle into the barrier.
U.S. Pat. No. 4,318,079 discloses a combination barrier having a gate arm and a vehicle barricade having tiger teeth. Two bell cranks are operated in response to an electric motor for causing simultaneous pivoting of the signal barrier with the tiger teeth. This device suffers from the disadvantages of only being able to utilize a small gate arm which only extends over a portion of the roadway. Further, this device is relatively complex and requires a high degree of maintenance.
The disclosed invention provides a novel and unique vehicle barrier having a low pivotal vehicle barricade and a cooperating pivotal signal barrier. The vehicle barricade and the signal barrier operate simultaneously in response to actuation of an hydraulic cylinder and piston assembly. The signal barrier pivots in response to operation of a ball nut which is actuated through a linkage arm connected to the barricade and moveable therewith in response to actuation of the hydraulic system. The device is simple in construction and low in maintenance. Consequently, one skilled in the art will appreciate that the disclosed vehicle barrier is a significant advance in the art.